When a conventional optical receiver circuit is used, it is difficult to achieve noise reduction or provide a multichannel capability due to a considerable circuit area increase. Disclosed is an amplifier for optical communications that includes a CMOS inverter, which has a PMOS transistor and an NMOS transistor; an input terminal, which inputs a signal into the CMOS inverter; an output terminal, which outputs a signal from the CMOS inverter; a power supply, which is connected to the CMOS inverter; a first element and a second element, which are respectively connected to the CMOS inverter; and two types of power supply paths, which are in opposite phase to each other.